Detection of target biomarkers permits the diagnosis and prognosis of a particular disease associated with the target biomarkers. Cardiovascular Disease (CVD), which includes coronary heart disease (CHD) and venous thrombo-embolism (VTE), is the leading cause of death in the United States, with an average of one death every 34 seconds and an associated cost of approximately $400 billion.
Among the CVD related illnesses, CHD is the single largest killer of Americans. Early and accurate diagnosis of CHD, especially in an emergency room setting, is crucial to design an appropriate patient care strategy. By measuring the levels of particular biomolecules, especially multiple biomolecules simultaneously, e.g., multiple cardiac markers simultaneously, in the blood, emergency room physicians can quickly determine whether patients have actually suffered a coronary event.
Several important cardiac marker proteins have been identified and routinely used in the current clinical practice. For example, cardiac troponin I (cTnI) is widely used as a standard biomarker based on its absolute cardiac specificity and its long serum half-life (7-10 days). Additionally, a rapid increase of myoglobin (MG) level in bloodstream following heart attack allows for a rapid patient evaluation. B-type natriuretic peptide (BNP) is useful for the emergency diagnosis of heart failure and for the prognosis in patients with acute coronary syndromes (ACS). C-reactive protein (CRP) is an important prognostic indicator of CHD and ACS.
Similarly, detection of VTE or for a heightened risk of VTE may be accomplished by monitoring and quantifying levels of particular anticoagulants in a patient's bloodstream. VTE is the third leading cause of CVD, affecting 1 per 1000 persons (1% in the elderly) and includes deep vein thrombosis, lung embolism, cerebral venous thrombosis, and purpura fulminans.
When the haemostatic system in human body is unregulated, due to either coagulation problem, or more commonly, due to impaired capacity of natural anticoagulant mechanism caused by anticoagulant deficiencies, the body has a predisposition to fatal venous thrombo-embolism. Protein C (PC), protein S (PS), antithrombin III (ATIII), and plasminogen (PLG) are four major anticoagulants in blood. Deficiency in PC, PS, or ATIII was reported to significantly increase the risks of VTE, and altogether account for about 15-20% of VTE cases. Therefore, accurate diagnostic tools for early detection of these deficiencies are invaluable to prevent the fatal VTE complications and a simultaneous quantification of these four anticoagulants in blood is beneficial for the accurate diagnosis of the actual cause of an abnormal clotting.
Due to the extremely low levels of the biomarkers (pM˜nM) associated with both CHD and VTE, as well as the presence of other structurally similar biomolecules in blood, a frequently used assay method is enzyme linked immunosorbent assay (ELISA). Although very accurate, it is time-consuming (hours to days), expensive, and technically complicated. Commercially available test kits for anticoagulants, BNP, cTnI, and CRP can provide fast, easy, and point-of-care assays. However, they usually provide only qualitative single biomarker information and most of the assay kits are relatively expensive, and may only be used a single time.
TABLE OF ACRONYMSA number of acronyms are used in this application. The followingtable of acronyms will aid readers of this application.NGPRNanogold Particle ReagentNMPRNanometal Particle ReagentSAMSelf-Assembled MonolayerNGP-SAMNanogold Particle with Self-AssembledMonolayerVTEVenous Thrombo-EmbolismCVDCardiovascular DiseasePCProtein CPSProtein SATIIIAntithrombin IIIPLGPlasminogenCHDCoronary Heart DiseasecTnICardiac troponin IMGMyoglobinBNPB-type natriuretic peptideACSAcute coronary syndromesCRPC-reactive protein